In the manufacture of laminates, especially decorative laminates, it has generally been necessary to somehow treat or condition the backmost side of the laminate before it can be readily adhered to a substrate. For example, in the production of horizontal and vertical decorative surfaces, decorative laminates of up to about 1/16 inch in thickness are adhesively bonded to substrates, usually flakeboard etc., by coating the side of the substrate to which the laminate is to be bonded, with a low cost, water borne adhesive such as urea-formaldehyde or polyvinyl acetate latex (white glue). In order to acheive effective and long-lasting adherence of the laminate to the substrate, it has been necessary to sand the backmost surface of the laminate because this surface is normally smooth due to the use of a glassine separator sheet in the laminate manufacture. Attempts have been made to eliminate the sanding operation because of its expense and undesirable dust production by attaching a polyvinyl acetate layer to the backmost side of the laminate and then activating this layer with heat or a solvent before applying it to the substrate, see U.S. Pat. No. 3,551,283 and No. Re. 27644.
This method of circumventing the sanding operation has not proven to be commercially attractive and alternative means have been sought for some considerable time.